Application Case Study
Product T21 Thermal Differential Switch
Application
Pump Protection
The Application
In process industries, it is crucial to be able to detect if a pump is operating against a closed valve or plugged line
downstream of the pump. If the pump continues to operate against a closed valve or plugged line, the temperature
of the fluid being pumped will increase. This condition has to be avoided at all costs, especially when using volatile
or explosive fluids. Process plants want to ensure that fluid is always flowing in the pipe to prevent overheating and a
potentially explosive environment or unsafe condition.
The Solution
The solution involves installing an SOR® Thermal
Differential Flow Switch in the discharge piping
from the pump. The T21 detects movement of
fluid in the pipe and can thus be used to detect
either loss of fluid to the pump or operation in a
deadheaded situation. When the flow rate drops
below the minimum flow rate, the flow switch will
indicate an alarm condition and/or shut down
the pump. The flow switch has no moving parts;
therefore, it provides high reliability and long life.
T21 Thermal Differential
Sensor
Centrifugal Pump
The T21 can also be used to protect pumps from running dry. A petroleum company uses booster pumps at intervals
along the length of a pipeline to keep oil moving through the line. On certain occasions, there is very little oil in the
pipes. To prevent premature pump failure and expensive field service to replace the pumps; the T21 can be used as
a level switch. The level switch shuts down the pump and alarms the control room upon loss of contact with the oil
in the pipeline. A switch is located in the control room to manually reset the line. The small size of the sensor allows
installation into small diameter pipes without modification.
The Results
The user receives pump protection and ensures a safe environment for the plant personnel. The T21’s fast response
time permits detection of a low flow condition generally within less than ten seconds. The T21 can also be used to
protect pumps from running dry. The switch operation is not affected by changing dielectric constant.
The T21 has no moving parts to wear out or break.
Thermal Differential Flow Switches are used in broad range of
process industries, including fertilizer, chemical, metallurgical and
hydrocarbon processing to detect deadheaded pumps. The unit
can be placed in the field with confidence that it will perform
continuously with little or no maintenance.
Ordering Information
Model NumberT21-DF6D-CS-RR
EAC-8A-CS-2-RR
3/4” Process Connection
316SS Sensor
2” Insertion Length
Form 1151 (08.14) ©SOR Inc.
Design and specifications are subject to change without notice. For latest revision, go to sorinc.com.
913-888-2630 • 800-676-6794 USA • 913-888-0767 FAX • sorinc.com